Method for controlling a refractive index of a dry plating film and method for making a dry plating built-up film

Abstract

A method for making a dry plating built-up film comprises providing silicon carbide as a starting source and subjecting to dry plating while changing a concentration of a reactive gas continuously or intermittently to deposit and form, on a substrate, a thin film having different refractive indices along its thickness. A method for making a sputter built-up film is also described, which comprising providing silicon carbide as a target and subjecting to sputtering while changing making electric power against the target continuously or intermittently to deposit and form a thin film having different refractive indices along its thickness.

What is claimed is:  
     
       1. A method for making a sputter built-up film which comprises the steps of providing silicon carbide as a target, and subjecting the silicon carbide to sputtering while changing electric power against the target continuously, thereby depositing and forming, on a substrate, a thin film having different refractive indices along its thickness. 
     
     
       2. A method according to  claim 1 , further comprising changing a concentration of a reactive gas continuously or intermittently. 
     
     
       3. A method according to  claim 1 , wherein said silicon carbide used as the starting source consists essentially of a silicon carbide sintered product which is obtained by sintering a homogeneous mixture having a density of 2.9 g/cm 3  or over and made of silicon carbide powder and a non-metallic sintering aid. 
     
     
       4. A method according to  claim 1 , wherein said built-up film is used as an anti-reflective film. 
     
     
       5. A method according to  claim 1 , wherein the sputter build-up film has a refractive index which changes in a wave form selected from a rectangular wave, triangular wave and sine wave along the thickness thereof.